M1078A1 2003 Bad transmission problems

[Keith Knight]

Without listing all the symptoms leading to the final nail in its coffin here is the last thing I found. After removing a cover an the back of the transfer case gaining access to the out put speed sensor area I found two and a HALF small roller bearings measuring about 3/16in long by 1/16in diameter. With something that small i would imagine pieces could be every where and I now need a complete rebuild. But I lack transmission knowledge.
Does any have any advise or experience with this, none of the local Detroit Allison shops have any experience with this model or seem interested in helping. Allison does not rebuild this model so if anyone could point me in a direction of a company with experience or knows of a better solution I'm all ears.
I would greatly appreciate any wisdom or advise you would be willing to share!
Thanks
Keith

 

[Suprman]

I have a good replacement on hand. I know the transfer case can be separated and replaced independent of the transmission and vice versa.
Will

 

[Keith Knight]

I would think I would need both the transmission and T-case sense they share the same fluid. Whats the year, serial number, and how many miles on it? As they had numerous wire harnesses for it. And of coarse how much?

 

[Suprman]

I have one from a 2004 M1083A1 with 800 miles past 2013 depot rebuild. I have a second one from a M1088 tractor that was depot rebuilt in 2001. I had been driving this truck before I sold the engine from it. Both are complete with t-case. It would be a good idea to reuse your harness. Email me will atpawnking dotcom.
Will

 

[Lmtv772]

Pm'ed you

 

[Keith Knight]

I picked up a used transmission but was still wondering what may have caused the problem to begin with. Any suggestions?

 

[Suprman]

Maybe thats why the military got rid of it or maybe someone tried to run it low on fluid after it was drained. Allisons in general are robust reliable units.

 

[Lmtv772]

Keith I think what you suggested sound most plausible. The pump in your transmission broke (that's why there was no fluid coming from the port). that lack of fluid took out the test of the transmission.

 

[Suprman]

I thought the torque converter is the fluid pump.

 

[Lmtv772]

I thought the torque converter is the fluid pump.

You know more than I do about these transmission. You're probably right

 

[Suprman]

I used to play with old GM cars. I kind of learn as I go. I have one here that gives me a solenoid error and won't go into gear. I played with it a bit but didn't have a lot of time to give it. It's a first gen truck but has wtec3 like the A1 trucks. The wtec2 is a bit easier to diagnose from a lay mans perspective. It was a NY truck and has more than its fair share of electrical contact corrosion. Between the military manual and the allison troubleshooting guides plus some pin out sheets I am confident with time I can figure it out. The military has been running these trucks for over 20 years someone has to be rebuilding the transmissions somewhere. A good old school heavy truck transmission shop could take apart and put it back together with a parts breakdown manual. I'm sure any internal part can be ordered or sourced. A while back I sold a guy a HT740 trans reman in the mil crate. He had installed it and it was giving him some problem I was going to swap it for another but he wanted to look into it himself. A day later he sent me pics of it completely disassembled on his garage floor and he found a piece of shop rag inside that was overlooked at mil rebuild. 60 bucks worth of parts later it was back together and running right. These transmissions may seem intimidating to us but it's just a fancier version of the older models.

 

[Keith Knight]

From what I understand there is a secondary pump for the transfer case that uses the passenger side PTO output of the transmission to run it.
Allison rebuilds practically every model except the MD 3070. I did find 3 different companies that would rebuild 2 of them were right at $8,000 and 1 for $3,500 plus freight. But only one of the companies spoke with knowledge of the transmission and they were the $8,000 price tag.

 

[Suprman]

Winch trucks have a standard pto attached to the trans there. It is possible the t case has its own circulation pump though. Most divorced t cases do. This is the first married one I have had. Some parts like valve body or solenoid actuators are under the pan and intended to be replaceable without trans removal. It is possible your little bits were left floating around in the trans from a sloppy rebuild at one time.